Technical Field
The present invention relates to a porous honeycomb structure comprised of co-catalyst particles and inorganic binder particles, and producing the same.
Related Art
A honeycomb structure made of cordierite or SiC or the like is used to purify a vehicle exhaust gas. More specifically, an exhaust gas purification catalyst having a co-catalyst, which is made of a ceria-zirconia solid solution or the like, and a noble metal catalyst both supported by an inorganic binder is used as the honeycomb structure.
In recent years, attempts have been made to construct a honeycomb structure using a co-catalyst component or the like. More specifically, as proposed in WO2010099275, a mixture of an inorganic binder and an oxide-based component including a ceria-zirconia solid solution and a zeolite is formed and fired to a honeycomb structure.
However, there is a problem with the above conventional honeycomb structure that high strength and high exhaust gas purification performance cannot both be achieved. Particularly, the strength is prone to be insufficient since the above conventional honeycomb structure has relatively many sites where co-catalyst particles are weakly bound. Indeed, an increased amount of inorganic binder can lead to increased strength of the above conventional honeycomb structure, however, which may reduce the specific surface area and degrade the exhaust gas purification performance.
In consideration of the foregoing, exemplary embodiments of the present invention are directed to providing a honeycomb structure having both higher strength and higher exhaust gas purification performance, and a method of producing such a honeycomb structure.